This disclosure concerns a method and a monitoring device for detection of an Equivalent Isotropically Radiated Power (EIRP) degradation of a transmitter of a satellite transmitting RF signals and being subject to a repeating ground track.
The EIRP characterizes radio frequency (RF) signal transmission power of a transmitter of a satellite in a direction of the main satellite antenna beam. It depends on the directivity of the satellite antenna (antenna gain) and the input RF transmission power.
Besides an RF environment of the receiving ground antenna and the receiver and antenna characteristics, the signal-to-noise ratio (C/N0) of the received signal on ground depends on the satellite EIRP.
For this reason, the EIRP is an important parameter for characterizing the signal transmission power to be monitored for any satellite transmitting RF signals in a satellite system or satellite service, for example for GNSS systems, like GPS, Galileo, Beidou or GLONASS, and SBAS systems like EGNOS or WAAS. The quality of the received RF signal in terms of signal-to-noise ratio depends on the EIRP.
Routine periodic measurements of a boresight EIRP are regularly conducted by means of dedicated measurement campaigns using high-gain antennas, for example 20 m high-gain dish antennas. For reasons of cost and effort, such measurement campaigns are usually not set up more often than once per month. However, there is the need for more frequent EIRP measurements or even for permanent EIRP monitoring in order to detect any anomaly in signal transmission power or any variation in the satellite antenna gain pattern within near real-time.